Flour mites (Acarus siro) are very tiny little creatures, but they can still be pests. A flour mite, sometimes called a grain mite, appears harmless. It is just a little over a tenth of an inch long. It has a soft white body, and like all mites, it has eight legs, except in the larval stage when it has only six legs. The legs are pinkish to brownish in color. Whenever there is a severe infestation of these pests, the surface they are on appears to be covered with a fine dust.
You’re unlikely to want to eat any dry goods visibly infested with these mites, and you may even be hesitant to do so after brushing or washing them away, but these flour pests are harmless if eaten. The chances are you’ve knowingly or unknowingly eaten a mite or two in the past, just as you may have ingested an occasional gnat or other tiny creature. There are a few people who are allergic to A. siro, although having a mite allergy is somewhat rare. Those that do have a mite allergy are usually allergic to mite bites, but these particular mites don’t bite.
Life Cycle of the Flour Mite
A flour mite doesn’t live for long. Its life span can be as short as 9 days or as long as a month, depending upon various conditions. The life cycle starts with the egg. A female mite will lay up to 30 eggs per day for a period of several weeks. The maximum number of eggs a female will lay during her lifetime can approach 800. It is obvious then that even if these little bugs don’t live long, a colony of them can grow to very large numbers and can be present in one location for a long time.
Once an egg has hatched, the flour mite enters its larval, or juvenile, stage. Most will eventually emerge from this stage as adults. A few however will develop small suction-like appendages, which allow them to hitch rides on pets, boxes, or whatever is moving by and thereby travel to another location. Most adults will stay put, as long as a food source is available.
Getting Rid of Flour Mites
While they are distantly related to the flea, flour mites are not quite as difficult to get rid of. Still, when you are trying to eliminate these arthropods, you have the different life cycle phases to deal with. While a pesticide will take care of them in short order, you need to be careful about using pesticides around food items. The best way to eliminate the mites is to remove all of the food items, which can mean cleaning out a pantry or emptying a grain bin. When packages of flour, cereals, or grain are returned, it needs to be made certain that there are no mites present in these foods or on the packaging, or the problem can start all over again.
If there is a redeeming feature for the homeowner, it’s that A. siro are choosy about what they will eat, which is mostly grains, cereals, and flour. They normally will not accumulate around other foods in a pantry, and if the foods they like are not there, they will shortly die off. Besides cleaning cupboards and containers to get rid of as many mites as you can find, the best way to eliminate them is simply to deprive them of their food supply. Just remember the one-month life cycle. If you’ve missed any of them, they may hang around for nearly that long, but after a month, there won’t be any left.
A. siro cannot travel long distances on their own, nor do entire colonies move from place to place. They won’t come marching in your front door, but you can carry a few indoors with you. This is most apt to happen when you’ve been out shopping for food, and a few mites hitchhiked either in some purchased grains or flour that was in an open container or on a box of cereal at home.
Another way to deal with these pests is to keep shelving and cupboard spaces well lit and dry. The mites seek out places where it dark, and somewhat moist, and of course where there is food. Damp packages of cereal or flour in a warm, dark cupboard can be a mite haven. If you see some in your flour and you don’t want to throw the flour out, you can always bake some bread with it. Some cooked mites would not be noticeable, but a large infestation could cause the bread to have a somewhat muddy taste. Another tactic is to put any suspected food item in a deep freezer for 24 hours. This will usually kill off the mites and their eggs.
Cleanliness isn’t really an issue with A. siro. They are not the same species as dust mites, or mites that eat dead skin, or those that live in your pillowcases. It’s good hygienic practice to keep places where you store food as clean as possible. What dirt or debris can do is to collect moisture, making a cupboard a comfortable place for these tiny arthropods to hang out in.